When was the Periodic Table of the elements invented?

In the year 1869, Dmitri Mendeleev who was a professor invented the first periodic table of the elements to teach his students and published it in “Principles of Chemistry”. He created a chart in a tabular form in which each of the 63 chemical elements was arranged as per the atomic mass order. The chemical elements are now arranged by their atomic number. Till now 118 chemical elements have been discovered.